Hearing aid



FIG. 1 is a top perspective view of a hearing aid, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is a side elevational view thereof, opposite that shown in FIG. 4;

FIG. 6 is a rear elevational view thereof; and,

FIG. 7 is a front elevational view thereof. 

The ornamental design for a hearing aid, as shown. 